A source tells the publication she "celebrated privately with Prince William and the children". She stepped out on Wednesday, January 10, for a solo engagement at the Reach Academy in Feltham, London.
The "Florrie" floral print dress isn't a new addition to the royal's wardrobe: The 36-year-old wore it while pregnant with Charlotte and clearly hung on to it for a potential pregnancy number three.
The Duchess chose a recycled blue dress.
This is a children's mental health charity for which Kate is a Royal patron, that helps pupils, teachers and parents. Online: "She will be spending the day privately". And in Brixton earlier this week, she donned a stunning salt and pepper coat by Canadian brand, Smythe, teaming it with an M&S jumper and a pair of Burberry pants.
Meanwhile, it's certainly not the first time the Duchess has recycled some of her favourite outfits. The art history graduate has a well documented passion for photography and recorded George's first day at Montessori and publicly released a number of pictures taken of her children over the years for special occasions.
And just weeks ago, she visited the Robin Hood Primary School in London to celebrate the school's gardening program, wearing a knitted black jumper, black leggings and her favourite brown knee-high boots.
She was first pictured wearing them at a photoshoot in 2004 and has pulled them out of the closest at multiple royal events since, including on worldwide trips with William and family events in England.